My vote goes to the Diamond Star cars from Chrysler/Mitsubishi's joint venture. You know, the Laser/Talon/Eclipse. I haven't had a single one come thru the dealership that wasn't a mechanical nightmare. The best combination seems to be the anemic 1.8L engine with a manual tranny. The automatics were crap, and don't even get me started on what a pile of junk that DOHC 2.0L engine is! Timing belt chucking, valve smacking, oil drinking piece of trash.
The electronics sucked the fat one too, not to mention the interior looked like it was designed by a teenager. You can't get the steering wheel more than 2" off your lap no matter where the seat or wheel is positioned if you're over 6' tall. Actually, the whole car has a certain radio-controlled racer look to it. Looks like the designers bought a R/C car at Wal-Mart and made it life-sized.
I know there's guys out there that make these cars incredibly fast, but anything can be made to go fast if it's light enough, and you throw enough boost and nitrous at it. Going fast reliably is another story, and these sorry excuses for transportation definitely get a failing grade in that department.
I'll be so happy when the majority of these little turds end up crushed so the kids that come into the dealership stop bugging me about finding them one.